Charged particle beam writing apparatus and method for diagnosing DAC amplifier unit in charged particle beam writing apparatus

Abstract

The charged particle beam writing apparatus includes a position deflection control circuit. First digital data that is to be used for circuit diagnosis is transmitted from the position deflection control circuit to the DAC amplifier unit at the same rate as a rate of writing on a product reticle and stored in a first maintenance memory. Second digital data is output from a digital section included in the DAC amplifier unit in response to the first digital data and stored in a second maintenance memory. A maintenance clock generator generates a clock signal and reads the first digital data stored in the first maintenance memory and the second digital data stored in the second maintenance memory. The first digital data thus read is compared with the second digital data thus read for each bit to diagnose the digital section.

1. A method for diagnosing a DAC amplifier unit in a charged particle beam writing apparatus comprising:
 transmitting pattern data from a control calculator to a deflection control circuit; 
 generating first digital data based on the pattern data in the deflection control circuit; 
 storing the first digital data in the deflection control circuit; 
 transmitting the first digital data to a DAC amplifier unit at the same rate as a rate of writing; 
 storing digital data which are outputted from the digital section, in the DAC amplifier, as a second digital data; and 
 comparing the first digital data and the second digital data for each bit to diagnose the digital section. 
 
     
     
       2. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 1 ,
 wherein data having multiple bits that are repeatedly reversed at the same time are used as the first digital data. 
 
     
     
       3. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 1 ,
 wherein the digital section is diagnosed either before or after the writing. 
 
     
     
       4. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 1 ,
 wherein, when the first digital data does not match the second digital data, information on bits that do not match each other are output as the result of the diagnosis. 
 
     
     
       5. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 4 ,
 wherein the digital section is diagnosed either before or after the writing. 
 
     
     
       6. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 4 ,
 wherein data having multiple bits that are repeatedly reversed at the same time are used as the first digital data. 
 
     
     
       7. The method for diagnosing the DAC amplifier unit in the charged particle beam writing apparatus according to  claim 6 ,
 wherein the digital section is diagnosed either before or after the writing. 
 
     
     
       8. A charged particle beam writing apparatus comprising:
 a deflection control circuit for generating first digital data based on pattern data, by a control calculator of a charged particle beam writing apparatus, in a deflection control circuit, storing the first digital data in a first maintenance memory; 
 a DAC amplifier unit including a digital section, a second maintenance memory, and a DAC, wherein the digital section is adapted to receive the first digital data from the deflection control circuit and is adapted to output the first digital data as a second digital data, the second maintenance memory adapted to store the second digital data which is outputted from the digital section, and the DAC is adapted to convert the second digital data into analog data; and 
 a diagnosis unit that causes first digital data to be transmitted from the deflection control circuit to the DAC amplifier unit at the same rate as a rate of writing and stored in the first maintenance memory, and compares the first digital data with the second digital data stored in the second maintenance memory for each bit to diagnose the digital section. 
 
     
     
       9. A charged particle beam writing apparatus according to  claim 8 ,
 wherein the control calculator serves as a diagnosis unit. 
 
     
     
       10. A charged particle beam writing apparatus according to  claim 8 ,
 wherein the write data generation circuit receives the pattern data from the control calculator of the charged particle beam writing apparatus; 
 the write data generation circuit transmits the generated write data to the deflection control circuit, 
 the deflection control circuit then generates a first digital data based on the received data. 
 
     
     
       11. A charged particle beam writing apparatus according to  claim 8 ,
 wherein the diagnosis unit generates an alarm when information on bits included in the digital data pieces do not match each other when compared. 
 
     
     
       12. A charged particle beam writing apparatus according to  claim 8 ,
 wherein the diagnosis unit diagnoses the digital section of the DAC amplifier unit during the writing.